National Biodiversity Strategy Plant Invasion in Italy an Overview a Thematic Contribution to the National Biodiversity Strategy Plant Invasion in Italy an Overview

A thematic contribution to the National Biodiversity Strategy Plant invasion in Italy an overview A thematic contribution to the National Biodiversity Strategy Plant invasion in Italy an overview

Ministry of Environment, Land and Sea Protection Nature Protection Directorate Director General Aldo COSENTINO

Italian Society of Botany President Francesco Maria RAIMONDO

Interuniversity Research Center “Biodiversity, Plant Sociology and Landscape Ecology” Sapienza University of Rome Director Carlo BLASI

© 2009 All rights reserved: Editors: Ministry for the Environment Land and Laura Celesti-Grapow, Francesca Pretto, Giuseppe Brundu, Emanuela Carli & Carlo Blasi Sea Protection Assistants to the editors: Nature Protection Directorate Ilaria Anzellotti, Sandro Bonacquisti, Piera Di Marzio & Barbara Mollo

Design by Palombi & Partner S.r.l. Photos by: Via Gregorio VII, 224, M. Adorni, A. Alessandrini, E. Barni, D. Bouvet, G. Brundu, E. Carli, 00165 Roma G. Ceffali, G. Domina, P. Ferrari, B. Foggi, L. Gariboldi, L. Ghillani, J. Grapow, F. Pretto www.palombieditori.it Front cover: Carporbotus acinaciformis. PHOTO: E. Carli Printed in April 2009 Palombi & Partner S.r.l. Attached CD-ROM: Non-native flora of Italy The project on the non-native flora of Italy

The uncontrolled spread of species from other geographical areas, introduced either intentionally or accidentally by man, is considered to pose one of the most serious threats to the conservation of biodiversity on a global scale, and has significant socio-economic and health repercussions. Inventories of non-native species compiled on a national scale thus represent a fundamental scientific tool for the correct management of invasions of such species. The project “A survey of the non-native flora of Italy”, promoted by the Nature Protection Directorate in collaboration with the “Biodiversity, Plant sociology and Landscape ecology” Inter- university Centre of the ‘Sapienza’ University of Rome, and completed in two phases between 2005 and 2008, was aimed at gathering, using a standardized system, information on the non- native vascular flora growing spontaneously in Italy and at identifying, among the high number of plant species present, the few that may, owing to their invasiveness or negative impact potential, pose a threat to the environment, human health or economy.

The overall situation in Italy is not particularly critical insofar as our country is characterised by a marked environmental heterogeneity and by a relatively high state of conservation, both of which tend to hamper major invasive events. Nevertheless, there are some seriously critical situations, and in general the phenomenon of plant invasion has progressed quickly recently; the natural systems, weakened most by the leading anthropic transformations within the environment, might no longer be able to endure the impact of man-made changes induced at ever-increasing speed and intensity such as the introduction of new species.

A database that may be used in a national strategy aimed at preventing the spread of harmful invasive species was prepared for each administrative region. A nationwide network of experts, set up to collect the data, identified 1,023 species. Among them 163 species are considered invasive, i.e. capable of spreading fast, and 203 species have been reported to exert some kind of negative impact in Italy, on the environment, human health or the economy. Invasive species that have an ecological impact were analysed in more detail.

Although invasive plants are concentrated above all in areas of intense human activity, such as man- made and agricultural areas, there are several natural environmental contexts in which the introduction of invasive species can pose a threat to the conservation of biodiversity and to ecosystem health e.g. wetlands, riparian areas, hygrophilous woods and coastal areas.

The attached CD containing the database testifies to the extraordinary knowledge available on a regional scale. This wealth of information is obviously essential for the definition of national strategies and action plans aimed at counteracting the spread of particularly invasive plant species.

In the near future, the Ministry plans to make the most of the work carried out so far by implementing a plan aimed at carefully monitoring the spread of those species that pose the greatest risk to human health, the environment and agriculture.

Stefania Prestigiacomo Minister of Environment, Land and Sea Protection

Senecio inaequidens. 1 Photo P. Ferrari Non-native flora Research director of Italy National team Carlo BLASI Scientific coordination of the research project L. Celesti-Grapow, G. Brundu, I. Camarda, L. Viegi, C. Blasi

Advisory group Technical and scientific support: F. Pretto, E. Carli, S. Bonacquisti Database: E. Dominici

Regional Experts ABRUZZO: F. Conti, A. Manzi; ALTO ADIGE: T. Wilhalm; BASILICATA: S. Fascetti; CALABRIA: L. Bernardo, C. Gangale, N.G. Passalacqua, D. Uzunov; CAMPANIA: V. La Valva, E. Del Guacchio; EMILIA-ROMAGNA: A. Alessandrini, G. Bracchi, N. Merloni, M. Pellizzari, F. Piccoli; FRIULI-VENEZIA GIULIA: L. Poldini, M. Vidali; LAZIO: F. Pretto, L. Celesti-Grapow, E. Carli, E. Lattanzi, C. Blasi; LIGURIA: S. Peccenini, R. De Mattei, A. Di Turi; LOMBARDIA: E. Banfi, G. Galasso, S. Assini, G. Brusa, L. Gariboldi; MARCHE: L. Gubellini; MOLISE: F. Lucchese; PIEMONTE: C. Siniscalco, E. Barni, A. Soldano; PUGLIA: S. Marchiori, R. Accogli, P. Medagli; SARDEGNA: I. Camarda, G. Brundu, L. Carta, M. Manca; SICILIA: P. Mazzola, G. Domina; TOSCANA: P.V. Arrigoni, L. Viegi, M. Boracchia, G. Ferretti, M. F. Palla; TRENTINO: F. Prosser; UMBRIA: M.R. Cagiotti, A. Ranfa; VALLE D’AOSTA: M. Bovio; VENETO: M.C. Villani, S. Carlin, N. Tornadore

Expert group for archaeophytes A. Alessandrini, P.V. Arrigoni, E. Banfi, F. Conti, G. Galasso, P. Mazzola, L. Poldini

Taxonomy and nomenclature revision E. Banfi, F. Conti, G. Galasso

Acknowledgements We wish to thank: G. Abbate, M. Adorni, A. Albano, L. Baker, M. Ballero, G. Barberis, M. Bassignana, E. Bona, F. Bonafede, F. Bonali, G. Branchetti, G. Ceffali, A. Colatore, S. Comin, B. Dalla Bona, L. Delfini, P. Di Marzio, P. Ferrari, F. Festi, F. Fiandri, B. Foggi, S. Frattini, L. Ghillani, F. Giordana, Gruppo Botanico Milanese, Gruppo Flora Alpina Bergamasca, A. Guiggi, M. Iberite, M. Kleih, I. Kowarik, M.L. Leporatti, U. Lodesani, P. Macchi, A. Marchetto, C. Mele, V. Morelli, F. Pauselli, F. Pavesi, G. Perico, M. Pinzi, P. Pyšek, E. Romani, C. Santini, M. Serafini, M. Sirotti, F. Vidotto, P. Viggiani, M. Vignodelli and E. Zanotti for their contribution to various aspects of the project.

2 Biological invasion: pet to pest in three generations

iotic invasions are becoming an increasingly widespread naturalization process were to stop at this point, it would enrich Bproblem that affects species belonging to all the main the local flora through the addition of a group of new species. In taxonomic groups as well as all types of habitat, whether what is usually a very small proportion of species, this process aquatic or terrestrial, natural or artificial. In his travels to new instead leads to the alarming, uncontrolled spread already lands, man has always taken a large number of species, both observed by Darwin, and later described by Elton (1958) in the intentionally, to surround himself with organisms he was used first book dedicated to biotic invasions, causing the well-known to in his homeland, such as domesticated animals and crop phenomena of loss of biodiversity and “globalization“ of the plants, and accidentally, such as most weeds, pathogens and earth biota, as well as serious economic damage and threats to parasites. Once they reached the new land, however, only a small human health. The reason for why some species become invasive proportion of these species reproduced spontaneously and pests has, in recent years, become the object of intense research, spread in the wild, becoming totally independent of man. with many hypotheses being proposed. Although multiple factors are involved in most cases and the history of each As regards plants, species that escape from cultivation remain invasion is different from that of others, some features are in the vicinity of the sources of seeds, e.g. in parks and gardens, common to all events leading to the invasion of a species, such not growing beyond the seedling state in most cases; in some as man’s responsibility in transporting them beyond major cases, they reproduce for a few generations, without forming natural biogeographical barriers (e.g. oceans), and in making the established populations. Very few of the introduced species do recipient habitat more vulnerable. establish, and hence become part of the local flora. If the

Xanthium orientale subsp. italicum and Cycloloma atriplicifolium on sandy soil in the bed of the Po river. Photo L. Gariboldi 3 Short history of plant introduction in Italy

n the Mediterranean Basin, human-mediated dispersal, resulting I in plants being transported much further than they would have been by natural means (e.g. by wind), was already very intense in ancient times. One such example are the great civilizations that promoted intense maritime trade all along the Mediterranean coasts. From as far back as the 10th century BC, first the Phoenicians, then the Greeks, established cities and colonies long distances from their homeland, with which they maintained constant exchanges. Subsequently, the Romans, with their expansive culture and the building of a network of roads that paved the way for the dispersal of plants via land, became chiefly responsible for the spread of species in extensive areas of Europe, North Africa and Western Asia. The appearance of “exotic” plant species has always aroused considerable interest in Italy. After the importation phase into the colonies of Magna Graecia spread along the coasts of Southern Italy, the Etruscans are also believed to have contributed to the introduction of several useful species from the Eastern Mediterranean, and subsequently to their dispersal in the central area of the Peninsula. It was, however, in Roman times that a real explosion in the importation of non-native species occurred. The Roman Imperial era witnessed a passion for exotic plants, expressed mainly in gardens, where new species from the coasts of Africa and Asia, such as palms, were used to embellish the patrician villas, or to enrich the banquets and impress the guests with unusual dishes at mealtime. In Medieval times, the monks used the new plants for their healing properties, recording them in precious illustrated miniatures, and

This picture taken in 1899 documents the first record of giant hogweed (Heracleum mantegazzianum) in Italy. Standing under the large umbels is Emil Levier, the Swiss doctor who brought seeds of this plant back from a botanical trip to the Caucasus mountains he had undertaken with Stephan Sommier in 1890. They described the plant upon their return to Florence, dedicating it to their friend Paolo Mantegazza. They subsequently donated the giant hogweed’s seeds to several botanical gardens, but it soon escaped from cultivation and is now one of the major invasive species in Europe.

cultivating them in the medicinal herb gardens, which subsequently evolved into the famous botanical gardens in Renaissance Italy. The Botanical Garden of Padua for instance, founded in 1545 for medicinal purposes, became an important centre for the importation and exchange of seeds and plants from throughout the world; indeed, many species were introduced for the first time in Italy, or even in Europe, in this Ricinus communis, an archaeophyte introduced in Roman times. garden. Other information has been passed down to us thanks to Photo F. Pretto the art of herbarium-making, whose birth is attributed to the

4 Italian botanist Luca Ghini, and which had spread all over Europe are well adapted to human disturbance and easily thrive in man- by the mid 16th century. made habitats. Jutting out as it does into the centre of the Mediterranean, from However, an awareness of the damage invasive species can inflict the Alps down towards the coasts of Africa, Italy has always been upon the natural habitat, as well as on agriculture and human exposed to a considerable exchange of biota, and has always health, has grown following the development of intensive integrated a large proportion of these new species into the local agriculture, industrialization and urbanization, particularly in the culture, using them for a wide range of purposes (e.g. food, Po Plain in northern Italy, and of increasingly extensive trade and ornamental, healing, forestry, windbreaker, to consolidate road travel; indeed, in as far back as 1905 the botanist Saccardo embankments, to build utensils), many becoming so integrated observed that some exotic plants, such as Erigeron canadensis, as to form part of the country’s tradition (tomato), or to be were rapidly becoming “the worst invasive weeds in Italy”. adopted as the symbol of a region or a local landscape, such as This phenomenon has progressed far more quickly recently, the cypress in Tuscany, and prickly pears, which now invariably particularly since the 1950s following an increase in the rate of appear on postcards from Sicily. introduction of new species, changes in land use throughout Italy, Until some decades ago, the situation regarding plant invasions and synergy with other drivers of global change. The increased in Italy was not particularly critical on account of several factors pollinosis induced by Ambrosia artemisiifolia, the growing size of that limited, particularly in natural habitats, the large monospecific populations of species belonging to the genera monospecific invasions that have occurred elsewhere in the Reynoutria in riparian habitats and Carpobrotus in the fragile island world. These factors include: the great environmental ecosystems, are only some examples indicating that the situation heterogeneity; the varied orography of the territory, most of has changed. Indeed, these findings suggest that the natural which is covered by mountains or hills; the presence of extensive systems, weakened most by the leading anthropic transformations areas at high altitude in the two main mountain chains, i.e. the within the environment, might no longer be able to endure the Alps, which span Italy’s northern border, and the Apennines, that impact of man-made changes induced at ever-increasing speed run south along the entire length of the peninsula; the and intensity, and that one such impact, which has worldwide persistence of traditional forms of agriculture and grazing; the repercussions, is the spread of invasive species. historical exposure of resident species to other biota (Rejmánek et al. 2005); lastly, the long-lasting association with humans, Nelumbo nucifera, an ornamental plant, has become invasive in which means numerous species of the local Mediterranean flora freshwater habitats. Photo E. Carli

5 The project on the non-native flora of Italy

t is this context that led to the research I project “A survey of the non-native flora of Italy”, developed in the years 2005- 2008 and promoted by the Nature Pro- tection Directorate of the Italian Ministry for the Environment, Land and Sea Pro- tection. The main aim of the project was to provide an overall picture of the non- native vascular flora in Italy and to iden- tify, among the high number of species present, the few that may, owing to their invasiveness or negative impact potential, pose a threat to the environment, human health or economy. The wealth of information obtained from the vast, historical Italian botanical tradition, which proved to be dispersed in innumerable sources in the specialised literature, in museums and herbaria, was gathered using a standardized approach by a nationwide network of botanists. The data were then inserted into an integrated regional and national database, which thus constitutes the state of the art on the non-native vascular flora of Italy and provides the scientific basis for the development of plant invasion research and management in the country. While more detailed information can be found in the literature (e.g. Celesti- Grapow et al. 2009a,b,c), in this work (booklet and CD-ROM) we present a syn- thetic overview of the main results on the composition, structure, distribution and impact of the non-native flora of Italy, as well as some information on the species recorded. Solidago gigantea. Like the congeneric S. canadensis, it is widespread throughout northern Italy. Photo P. Ferrari

6 The non-native flora of Italy

Species diversity and structure

he non-native vascular flora of Italy Ancient and recent introductions T numbers 1,023 entities, including The non-native flora of Italy is composed of species and subspecies and thus 103 archaeophytes and 920 neophytes. accounts for 13.4% of all the Italian flora, Archaeophytes are plant species that were which currently comprises approximately introduced very early on, i.e. before the dis- 7,600 entities. This richness of the non- covery of America by European colonizers. native flora may be ascribed to the They consist above all of agricultural weeds A dried specimen of Amaranthus retroflexus marked geographic heterogeneity within in the oldest crops, such as cereals, which are (photo) in Cibo’s ancient herbarium (1532) is the first record of a spontaneously-growing the country; there are, besides species nowadays widespread. Archaeophytes, with neophyte in Italy. Photo D. Bouvet widely found throughout Italy, consisting the exception of agricultural weeds, are not largely of urban and agricultural weeds, usually included in lists of species that need many other species that are found in only to be kept under control; moreover, follow- in Italy is Amaranthus retroflexus. A dried one sector of the country, with 205 ing the introduction of new agricultural sample of this species, conserved in the species being present exclusively in the techniques, several archaeophytes that are Biblioteca Angelica in Rome, Gherardo Cibo’s Mediterranean region, which follows all associated with traditional agricultural tech- herbarium, testifies to the fact that this the coastline and covers southern Italy niques are already in decline. annual herb already grew spontaneously in and the islands, 193 in the Continental Neophytes are species that have been 1532; owing to the speed at which it spreads, region, which covers northern Italy and introduced since the discovery of America. it has since become one of the most harmful runs down the Apennines, while a further Although the distinction between agricultural weeds in Italy. 57 are limited to the Alps. archaeophytes and neophytes in the The spontaneous spreading of several other literature is often made by rounding the year neophytes, such as Impatiens parviflora, is off to 1500, important plants had already documented from the mid 16th century in been introduced in Europe by Columbus numerous sources. Nowadays, while ar- when he returned from his first voyage in chaeophytes are found prevalently in agri- 1493, e.g. corn (Zea mays), whose presence cultural systems, neophytes are mostly The archaeophyte Abutilon theophrasti is a widespread agricultural weed. in Italy is documented from 1495. The first typical of urban and industrial areas, waste- Photo L. Ghillani spontaneously-growing neophyte reported land, and along railways and road verges.

Impatiens parviflora. Photo P. Ferrari 7 invasive no record after 1950 163 62

naturalized 361 casual 437

Casual, naturalized, invasive species Casuals (i.e. non-established species, see page 10 for definitions) currently make up the most numerous group in the non-native flora of Italy. They consist prevalently of ornamental or edible species that have escaped from cultivation and grow in areas close to parental plants. As many as 524 species have become established entities in the Italian flora. They include 163 invasive taxa (i.e. taxa that spread very rapidly, even long distances from where they were originally introduced; see page 10 for definitions), and thus account for approximately 16% of the overall non-native flora. It should be borne in mind that not all the invasive species are spread throughout the country; indeed, some are confined to a very small area. Twelve invasive taxa are currently restricted to a small number of sites and are referred to as local invasive. Monitoring of these species is particularly relevant for management purposes, as some Bletilla striata is the only representative of the orchid family in the non- are renowned major invaders elsewhere and might be in the ini- native flora of Italy. Photo A. Alessandrini tial stages of a potentially harmful invasion process.

Polanisia trachysperma is naturalized in riparian habitats. Photo P. Ferrari

Polanisia trachysperma. Photo P. Ferrari

8 Where have they come from? The majority of the non-native species have been introduced into Italy from the Americas and Eurasia, followed by species of African origin and those that have been introduced from other regions in the Mediterranean Basin. The provenance of the remaining species varies considerably, ranging from tropical areas to Australasia, though the native range of many species introduced in ancient times could not be defined. A group of 19 entities, which includes major invaders such as species of the genera Reynoutria and Oenothera, results from hybridization.

62 387 109 Americas 99 Eurasia Africa Mediterranean Others

366 Apios americana, a species from North America that grows in riparian habitats. Photo M. Adorni

Sicyos angulatus, a climber that spreads above all in riparian habitats. Photo A. Alessandrini

9 Definitions of terms used in the project

In the project “A survey of the non-native flora of Italy”, we adopted the terminology proposed by Richardson et al. (2000) and elaborated by Pyšek et al. (2004); the following definitions have been modified from Celesti-Grapow et al. (2009b).

Non-native plants - (synonyms: alien, introduced, non-indigenous, exotic) plant species whose presence is due to intentional or unintentional human involvement.

Not recorded since 1950 - plant species that lack recent records, i.e. that have not been reported since the year 1950.

Casual plants - (synonym: not established) non-native plants that may flourish and even reproduce occasionally outside cultivation, but that eventually die out because they do not form self-replacing populations, and rely on repeated introductions for their persistence.

Naturalized plants - non-native plants that sustain self-replacing populations without the direct intervention of people.

Invasive plants - a subset of naturalized plants that produce reproductive offspring, often in very large numbers and at considerable distances from the parent plants, and thus have the potential to spread over a large area.

Local invasive plants - non-native plants that have been found to be invasive in only one or two locations.

Archaeophytes - non-native plant species introduced before the year 1492, i.e. before the discovery of America by European colonizers. This date is conventionally rounded off to 1500.

Neophytes - non-native plant species introduced after the year 1492. This date is conventionally rounded off to 1500.

Artemisia verlotiorum. Photo M. Adorni

10 Species distribution across the country

he number and density (i.e. number of these markedly disturbed sites. By far the Trecorded species in relation to the area highest number of introduced species in of the region) of non-native plant any land use type is recorded in urban species, as well as the proportion of non-na- areas, followed by industrial sites and tive species in the flora varies considerably from region to region and increases in relation to the size of the human population.The highest values are reported in the largest, most densely populated regions in northern Italy, such as Lombardy and Emilia-Ro- magna, which comprise a large part of the heavily cultivated and industrialized Po Plain. Smaller, less densely inhabited regions, by contrast, have the lowest values. The number of non-native plant species is greatest in man-made habitats (e.g. urban and industrial areas, wasteland, along railways and road verges), with the majority of the non-native flora being confined to

communication routes. flora is highest in regions such as Lom- The effect of human dis- bardy, Veneto, Tuscany, Liguria and Lazio, turbance on non-native where large cities (respectively Milan, species and the concentra- Venice, Florence, Genoa and Rome) are tion of such species in major tourist destinations in Italy, as well man-made habitats, par- as centres of intense trade exchanges. ticularly in urban habitats, Communication routes, such as road and are renowned patterns. railway networks, also afford excellent op- Besides disturbance, in- portunities for secondary dispersal of intense propagule (i.e. seeds vasive species. Indeed, some species are or vegetative parts capable known to have spread quickly and exten- of rooting) movement also sively along roadside verges: the rapid contributes to the patterns spread of Senecio inaequidens, along major we observed. Artificial Italian motorways, for instance, has been habitats, particularly cities, recorded since the 50s, while Chamaesyce act as centres in which nutans is known to typically spread along non-native species are first railways. introduced, whether deliberately or accidentally, and are further spread by man Top: Percentages of non-native species in the e.g. through planting, flora of each region mainly for ornamental purposes, in parks and gar- Bottom: Distribution and status of non-native dens. Indeed, the number species in 5 main land use types. (Some species of casual species in the are found in more than one type) Chamaesyce nutans spreads above all along railway tracks. Photo A. Alessandrini

11 Although most non-native species are found in artificial and agricultural areas, as many as 461 species occur in terrestrial and freshwater natural or semi-natural habitats. If compared with artificial and agricultural sites, the non-native flora in natural habitats is numerically lower, but proportionally harbours more invasive than casual species. Freshwater habitats tend to be among those invaded most; although they do not usually contain as high a number of species as artificial or agricultural sites, their non-native flora generally harbours a high proportion of invasive species, some of which are widespread, while others are confined to smaller areas but sometimes display a high degree of aggressiveness, even within single locations. The twelve species described as local invasive include 6 aquatic plants that are worthy of mention: Azolla filiculoides, Hydrocotyle ranunculoides, Lagarosiphon major, Ludwigia peploides subsp. montevidensis, Salvinia molesta and Spartina ×towsendii. Although they are still highly localized, they are spreading rapidly, and may become major pests in Hydrocotyle ranunculoides, a freshwater plant that is local invasive in Sardinia. the future. Photo G. Brundu Helianthus tuberosus is a representative of the Asteraceae, the most numerous family (112 species) in the non-native flora of Italy. Photo L. Ghillani

12 Lombardy, the Italian region invaded most

Gabriele Galasso & Enrico Banfi

Lombardy is the Italian region with the highest number of non-native species (545 out of a total of 3,220 spontaneous vascular plant species, but the number is growing) and of invasive species (84). This is due not only to the considerable size and heterogeneity of the territory, but also to agriculture, urbanization, industrialization, freight traffic and people flow, all of which are particularly intense in this region. The areas affected most by invasive species are: the Insubrian area, whose woods are invaded by evergreen species such as Trachycarpus fortunei and Ligustrum lucidum; the Po plain, which harbours many agricultural weeds and plants that modify the structure of residual woods, such as Robinia pseudoacacia, Prunus serotina, Quercus rubra, Spiraea japonica, Parthenocissus quinquefolia and Vitis sp.pl.; riparian habitats, where we find, among others, Reynoutria sp.pl., Amorpha fruticosa, Humulus japonicus and Sicyos angulatus; lastly, areas that are heavily urbanized or routes of communication and railways, which are almost always lined by Erigeron canadensis, E. sumatrensis and Senecio inaequidens. In the Alpine sector of the region, which is the least invaded area, worthy of note is Elodea nuttallii, which is one of the species that grows at highest altitudes (up to 1,890 m). The main threat to human health is posed by Ambrosia artemisiifolia, which is responsible for late- summer, autumn pollinosis, a constantly increasing phenomenon. The aim of the project “The non-native flora of Lombardy” (“La flora esotica lombarda”) launched in 2008 by the Lombardy Region and the Natural History Museum of Milan, is to compile a database and botanical manual on the non-native flora of the region with the collaboration of numerous professional and keen amateur botanists.

Senecio inaequidens. Photo L. Gariboldi

13 Are the Alps really threatened by non-native plant invasion?

Elena Barni & Consolata Siniscalco

Mountain regions, widely recognized as important biodiversity hot spots with rich, distinct floras, are increasingly threatened by invasive non-native plants as a consequence of anthropogenic changes. The Department of Plant Biology of the University of Turin conducted a study in the Western Italian Alps aimed at assessing the current distribution of non-native plants in the Alpine valleys in which man’s presence is most marked, and to determine what elevation these plants reach. There is a significant degree of non-native plant invasion up to 400-500 m a.s.l., mainly along rivers and roads, which act as corridors for propagule dispersal. As the elevation gradient increases, there is an exponential decrease in non-native plant species richness, with a low presence of non-native species in areas above the timberline. Three factors are believed to be the main drivers of this distribution pattern: harsh climatic conditions, decreasing anthropogenic disturbance and propagule pressure at increasing elevation. Consequently, higher mountain regions should, in theory, be less threatened by non- native plant invasions; there is, however, evidence, yielded by studies conducted in the Swiss Alps, that several species have spread higher in recent decades, probably as a result of global warming, the increasing use of land for tourism and rapid adaptive evolution. The non-native flora recorded in the Italian Alps is composed mainly of invasive species that are widespread in the lowlands throughout Europe. The degree of pre- adaptation to mountain conditions of non-native species in their native range may determine their invasive capacity at higher elevations elsewhere. Consequently, some non-native plants, such as Reynoutria japonica, Erigeron canadensis and Buddleja davidii, are frequent at medium elevations (1,100-1,400 m), while a few species, such as Impatiens glandulifera and Impatiens parviflora, which are native to the Himalayas, tend to occur at higher elevations. Indeed, particular attention should be paid to the introduction of cold-adapted plants from other mountain systems. The Italian Alps are thus threatened by non-native plants, though the invasion process is still in its early stages and appears to be proceeding relatively slowly, at least at higher elevation. This situation offers a unique opportunity to counteract the threat of invasion by taking preventive measures to conserve native biodiversity, avoiding the introduction of non-native species, controlling those that have been introduced deliberately (i.e. for cultivation purposes) or accidentally, and eradicating isolated populations as soon as they appear.

Buddleja davidii. Photo E. Barni 14 Solidago gigantea. Photo L. Ghillani

Plant invasion in riparian habitats in northern Italy

Silvia Assini, Francesco Bracco & Francesco Sartori

Riparian habitats, especially in northern Italy, are amongst those invaded most in the country. The vegetation in the upper courses of rivers is usually composed of well-preserved natural communities that prevent invasive plants from spreading, whereas the invasion process along medium-low courses is more active, particularly in the alluvial plains. The flora in the river beds in northern Italy is rather monotonous owing to the widespread presence of invasive species. The Polygonum-Persicaria communities in the Po Plain are often dominated by Bidens frondosa and Xanthium orientale subsp. italicum. Other invasive species include Lindernia dubia, Erigeron canandensis, Humulus japonicus, Lepidium virginicum and, locally, Ambrosia artemisiifolia, Corispermum marschallii and Eragrostis pectinacea. The environmental conditions and state of conservation of riparian woods may influence the invasion of non-native species; a strong structure and considerable floristic variety can repel aggressive invasive species, confining them to the wood’s edge. One such example is the oak-elm wood of the Bosco Siro Negri Natural Reserve, where Robinia pseudoacacia is now receding and no new non-native invasive species are growing. Amorpha fruticosa is the only invading species in willow woods (Salix alba) along the eastern Apennine tributaries characterized by drought conditions. A similar situation is observed in the willow-poplar woods (Salix eleagnos-Populus nigra) along the Piave river in the Venetian Plain. By contrast, in the eastern Po Plain, the herbaceous layer of high cover willow-poplar woods along the Brenta river is often invaded by several non-native species of the genus Impatiens. The presence of invasive plants in the weakly-structured, fragmented white willow woods of the central course of the Po is very high, the most aggressive species being Sicyos angulatus, Solidago gigantea and Bidens frondosa. As the white willow woods along the Ticino river and the western course of the Po river are more mature and their structure and composition stronger, the non- native species in this area are less invasive, the only exception being Solidago gigantea.

Bidens frondosa. Photo P. Ferrari

15 Plant invasion on Italian islands

sland ecosystems, which tend to be generally simplified and to contain lower numbers I of plant communities that have evolved in less competitive conditions than those found on the mainland they lie off, are particularly vulnerable to perturbances, including the impact of invasive species. Moreover, the flora and fauna on islands often include endemisms that have a high conservation value. On the islands in the Mediterranean Basin, non-native plants have accompanied the presence of humans for millennia and, since the mid 20th century, the invasion process has increased in parallel with the sudden marked changes in land use caused by the abandonment of traditional agricultural methods and the development of tourism. The latter, mainly concentrated during the summer months, has, by fostering the introduction of propagules, led to an increase in the number of non-native species. In the project on the non-native flora of Italy, particular attention was paid to the distribution and invasive status of non-native plant species on the numerous small islands and archipelagos that surround Italy, so as to provide a general overview of the composition and structure of their non-native flora and to highlight the main threats. Number of non-native species in 47 small islands

Opuntia engelmannii in Sicily. Photo G. Domina

The prickly pear cactus (Opuntia ficus-indica) in Sardinia. Opuntia is one of most numerous genera (19 species) in the non-native flora of Italy, largely because of its popularity among collectors of succulent plants. Photo G. Brundu

Besides Sicily and Sardinia, which are the largest islands in the Mediterranean and are regions into themselves, the project recorded the distribution and status of the Italian flora in a significant sample of 47 smaller islands. The highest numbers of non-native species were recorded on Elba, Ischia and Capri, which are among the most densely populated of these 47 islands. The figure shows the distribution and invasion status of one of the most typical species found on these islands, Opuntia ficus-indica, more commonly known as the prickly pear cactus. Opuntia ficus-indica in 47 small islands

16 Plant invasion along the Italian coasts

uman action has deeply transformed coastal areas that have been subjected most Hthe coastal landscape throughout Italy, to invasion processes are located in the and coastal habitats are currently Italian regions that attract the highest among those threatened most by anthro- number of tourists (e.g. Liguria, Tuscany, Number of non-native species in rocky or pogenic activities. Drainage of wetlands, e.g. Emilia-Romagna, Calabria, Sicily and sandy shores in the Tuscan Maremma and the Pontina Sardinia). floodplain along the Tyrrhenian coast, The most striking feature of the Italian changes in land use, the building of settle- coastal non-native flora is the presence of a ments and seaside facilities, as well as tourist high number of succulent species. It may, in- activities, have wiped out most of the natu- deed, be this particular trait (i.e. succulence), ral vegetation, changed the physical envi- an adaptation of plants to resist drought not ronment and promoted the spread of common in the native flora, that has allowed non-native invasive species. Indeed, invasive these species, which originate in the Ameri- species have, in recent years, become the cas and southern Africa, to establish so suc- latest expression of human impact. cessfully in these new areas in Italy. They are There are two main, quite distinct, types of cultivated extensively and are used locally Opuntia ficus-indica and O. dillenii on the coastal landscape in Italy: rocky coasts, which for a wide range of purposes e.g. as orna- island of Capraia, Tuscan Archipelago. Photo B. Foggi are unstable environments on account of the mentals, as windbreakers, for soil stabilisa- erosion processes they are subjected to by tion, for fencing, and as food (e.g. the edible the sea, and sandy shores with dunes, which fruits of the prickly pear). suffer the most serious human impact, such Some of these succulent species have spread as urbanization and seaside tourism. The non- spontaneously from the sites in which they native flora found in these rocky and sand were first introduced, and are, in some cases, dune coastal habitats is currently composed becoming a serious threat to the conservation of about 260 species (considering neophytes of biodiversity in coastal habitats, on both a alone, i.e. plant species introduced after the local and global scale, owing to the presence year 1500). Of these, 54 are invasive, while a of rare and endemic taxa, particularly on small further 87 are naturalized species that do not islands. Typical examples are the species display any invading tendency. The remaining belonging to the genera Carpobrotus, more species are generally ephemeral escapees commonly known as the Hottentot, and the from cultivations, particularly ornamentals, prickly pear cactus Opuntia. that do not establish in the local flora. The However, besides their ability to colonise Carpobrotus acinaciformis along the coasts

rapidly and occupy space, and consequently compete for water and light, little else is known about the impact of these species, nor have detailed analyses and quantitative assessments been conducted to assess how seriously they threaten the habitat. Given the intensification of these phenomena in recent years and the high number of newcomers, a deeper insight into the ecology of invasive species and their distribution along the coasts is urgently needed, as are studies on their impact, to be able to plan appropriate management interventions and set priorities Agave americana, a succulent species, on the island of Ventotene, Pontine Archipelago. Photo E. Carli for control aimed at conserving biodiversity.

17 Impacts and threats

he information available on the impact of T non-native species collected during the Italian project proved that general knowledge is somewhat scarce and frag- mentary, it being based in many cases on unverified observations. Indeed, experimental studies and further research aimed at verifying and evaluating the impact of all these species are urgently needed. On the basis of this survey, whose nature is merely preliminary, we found records of 203 species that have been reported to exert some kind of negative impact in Italy. The tendency of non-native species to gravitate around human activities is also reflected in their impact: the majority of the species reported to have a negative impact are agricultural weeds, which cause problems such as production losses and higher Ailanthus altissima, whose roots inflict serious damage on man-made constructions. Photo J. Grapow production costs due to the use of herbicides. Several studies indicate that the incidence of non-native species among such weeds has increased in the last forty years. Owing to the wealth of historical monuments and archaeological remains, a particularly relevant issue in Italy is the damage inflicted by invasive plants on the country’s historical Datura stramonium, heritage. Although the number of non-native fruit and seeds. species was found to be particularly low in the Photo P. Ferrari flora of archaeological sites, some can be particularly detrimental owing to the mechanical and chemical damage caused by their roots. A few, fast-growing woody species, such as Ailanthus altissima, Ligustrum lucidum and Acer negundo, have recently spread extensively on important remains, mostly in central and southern Italy; the fact that these species are dispersed by either wind or birds means that their seeds are easily transported onto the tops of monuments; this renders any measures taken to control them (usually limited to mowing) particularly difficult and expensive. A preliminary survey of the sources available found 42 species that have detrimental effects on human health, consisting above all of toxic or allergenic species. Datura stramonium, parts of the plant are toxic to humans and animals. Photo P. Ferrari

18 The spread of Carporbotus edulis threatens the survival of residual populations of Limonium sommierianum, endemic to the islands of Giglio, Montecristo and Giannutri in the Tuscan Archipelago. Photo J. Grapow

Most of the 88 species reported to have an ecological impact are either believed to directly threaten the conservation of biodiversity or alter ecosystem properties. It is noteworthy that all those species that have been classified as local invasive are included in this group and have, despite being highly localised, been shown to pose a threat to local biodiversity. The aquatic plant Lagarosiphon major, for instance, can build dense floating mats that prevent light from reaching the layers below, thus competing with other species and threatening the survival of aquatic invertebrates. The widespread invasion of this species in one area of the Garda Lake is believed to have been the main cause of the disappearance of Ranunculus circinnatus from the only surviving location in Trentino, where it was present until 1992 (Prosser, in Celesti- Grapow et al. 2009c). The most striking example of a threat to the conservation of biodiversity is probably the species of the genus Carpobrotus. They are spreading on the steep sea cliffs of the Italian islands, in habitats that had previously been conserved on account of their inaccessibility to man, and are seriously threatening the survival of rare and endemic entities. The studies undertaken so far indicate that riparian plant communities, wetlands and coastal habitats are those threatened most by non-native species. We illustrate some of these species in the next chapter.

19 Italian legislation on invasive plants

Giuseppe Brundu

Biological invasions are processes that should be tackled with adequate tools of international environmental legislation, as has been done for other global issues, such as climate change, marine pollution, biodiversity loss and deserti- fication. Legislation tools have so far mainly consisted of “soft laws”, i.e. international non-bonding resolutions, declarations and agreed principles, such as “polluter pays”, or the commit- ment to nature conservation resulting from the Stockholm Declaration, signed in 1972. However, a significant body of environmental legislation, either directly or indirectly related to biological invasions, has more recently been passed in a relatively short period of time. One example of such legislation is the Bern Convention. The Con- vention on Biological Diversity (CBD), ratified by Italy (L. n. 124/1994), calls Ipomea acuminata. Photo F. Pretto for the parties to prevent, eradicate and control those non-native species that threaten ecosystems, habitats and other species. The CBD has been adopted within many European and national regulations, such as the Italian DPR no. 357/1997 which has led to the implementation in Italy of the Council Directive no. 92/43/EEC. Italy has recently modified the text of its Constitutional Law (ex L.C. n. 3/2001) to intro- duce the term “ecosystem and habitat conservation” [117.2.s] as a national government priority. Nevertheless, the regions can pass ad hoc legislation on invasive alien species (IAS), [117.3] in a variety of fields closely related to biological invasions (e.g. human health, land management, conservation of cultural and environmental heritage, production, transfer and distribution of energy). Italian regions also have legislative powers [117.4] regarding “agriculture, forestry, hunting and fishing”. As regards invasive species in particular, Italy has not adopted tools such as the “environmental damage” and “environmental liability” principles, which may help tackle the problems related to the invasion of such species. No action has been taken either to update Italian legislation or to adopt international strategies such as the European Strategy on IAS, signed in 2003, or the “code of conduct on horticulture and invasive alien plants”, drawn up by EPPO. Only at a regional level do we find specific legislation on the regulation and control of IAS (e.g. the Lombardy law no. 10 dated 31/03/2008, the Sardinian regional landscape plan). Although non- native species are mentioned in several texts, somewhat contrasting terms are Oxalis pes-caprae. Photo E. Carli often used.

20 10 of the major plant invaders

The following fact sheets illustrate ten key examples of invasive species in Italy; they represent a wide range of invaded environments and have different forms of impact. Although these species are among the most harmful invasive plant species in the country, they are not necessarily the “top 10”. All the species described briefly here are neophytes (i.e. introduced after the year 1500), invasive (i.e. spreading fast), and are reported to have a significant negative impact somewhere in Italy. They are otherwise markedly different: some are widespread throughout the country (e.g. Ailanthus altissima), others are common at the regional level (e.g. Impatiens glandulifera in the north of Italy), yet others are highly localized; some are invasive in only a few sites, or even in one site alone, but are rapidly expanding (e.g. Heracleum mantegazzianum).

The examples provided are typical of the main natural environments that have been invaded, such as wooded (Prunus serotina) and riparian (Amorpha fruticosa) habitats, and include both terrestrial and aquatic plants. Besides species that pose a threat to natural systems, either by altering the abiotic environment (Robinia pseudoacacia) or by directly threatening biodiversity, both on a local (Reynoutria japonica) and global scale (Carpobrotus sp.pl.), we have also included one example of species that pose other types of threat, e.g. to human health (Ambrosia artemisiifolia).

The presence of the majority of these 10 species has long been known in Italy, and some have been included among the main threats to biodiversity and subjected to control measures within LIFE Natura projects (http://ec.europa.eu/environment/life/index.htm). We have, however, also included one example of a species that is still little known in Italy (Ludwigia peploides subsp. montevidensis), but has been reported to have a very harmful impact in other countries (e.g. http://www.eppo.org/ QUARANTINE/quarantine.htm). It is essential that such species be highlighted because it is in these species that countermeasures aimed at controlling and preventing further spreading may, given their limited presence, be effective.

As the examples selected are all renowned invasive species in Europe or worldwide, in the following fact sheets we provide some information on their invasion history and threats specifically in Italy; more general information may be obtained by consulting the numerous studies (e.g. Weber 2003, Galasso et al. 2008, DAISIE 2009) and internet sites dedicated to such species (e.g. http://www.issg.org/; http://www.daisie.ceh.ac.uk/; http://www.nobanis.org/; http://www.eppo.org/; http://ias.biodiversity.be/ias/; http://www.cps- skew.ch/english/info_invasive_plants.htm; http://www1.ci.uc.pt/invasoras/index.php).

21 AILANTHUS ALTISSIMA (MILL.) SWINGLE

TREE OF HEAVEN

Growth form: tree Family: Simaroubaceae Native range: China Introduction: ornamental

This deciduous tree is one of the most common invasive plant species in Italy, it being found ubiquitously in urban and ruderal areas. Introduced in the country in 1760, through Padua’s Botanical Garden, it was originally cultivated in order to breed the ailanthus silkmoth, which came from China, like the tree, fed itself on the foliage of this species and was supposed to replace the local silkworm. Ailanthus altissima was Photo J. Grapow subsequently widely cultivated as a garden ornamental plant and as a street tree, especially in cities, thanks to its robustness and capacity to grow in poor soils. It was already known to spread spontaneously in the mid 19th century, and has since extended its range in the country rapidly and efficiently owing to the huge number of seeds produced by the female trees (male and female flowers are on different trees), to the vigorous vegetative reproduction of its root suckers and to its rapid growth. It tends to establish itself in disturbed sites, such as along roads and railways, highway medians and wastelands, though it is also found in open woods and riparian habitats, where it displaces other species by forming dense thickets and by releasing a toxin that inhibits the growth of other plants (Kowarik, Säumel 2007). Its tolerance to drought and rocky conditions is such that tall vigorous trees can germinate and develop out of cracks in the pavement, in roofs, or even in vertical walls. This may cause serious problems due to the mechanical and chemical damage its extensive root system inflicts upon man-made constructions, such as buildings and infrastructures, and particularly to the historical heritage, i.e. ancient monuments and archaeological remains. The occurrence of this tree in important remains has in recent decades grown substantially; moreover, as its winged, wind dispersed seeds are easily blown upwards (e.g. on top of the Roman Colosseum, 50 metres above ground level), control measures, such as mowing, can be both difficult and costly.

Photo J. Grapow

22 AMBROSIA ARTEMISIIFOLIA L.

COMMON RAGWEED

Growth form: annual herb Family: Asteraceae Native range: Canada & USA Introduction: unintentional

This species is best known for its highly allergenic pollen, which is produced in copious amounts by the male flowers and becomes a stable component in the air in late summer in many areas in north-western Italy, particularly in Lombardy. Since it was first reported in Italy in 1902, it has spread rapidly, and became, by the 60s, widespread throughout northern Italy, especially in the Po Plain. Its range continues to expand, thanks to its enormous seed production and marked dispersal potential. Its preferred habitats Photo L. Gariboldi are human-disturbed areas such as ruderal or waste sites (e.g. roadsides, railways, gravel pits, construction sites), though it also grows along riverbanks. Besides its allergy-related impact on human health, it is also a significant agricultural pest, reducing the Photo P. Ferrari yield in many crops.

AMORPHA FRUTICOSA L.

FALSE INDIGO

Growth form: shrub Family: Fabaceae Native range: North America Introduction: ornamental

This shrub spreads mostly in riparian habitats, particularly in northern Italy. Introduced in the country in the late 18th century as an ornamental for its eye- catching flowers, it subsequently spread following its use for hedges and bank stabilization. Its presence in the wild was first reported in the mid 19th century, and it has since spread Photo M. Adorni extensively along stream and river corridors thanks to its efficient vegetative reproduction. It has now become biodiversity. It is one of the few species that have been widespread, particularly in the north, where it is found in the targeted by specific management strategies at the regional beds and along the banks of rivers in the Po Plain and the level: in Lombardy it is included in the list of invasive species neighbouring valleys. Although it is also found in ruderal sites, threatening biodiversity, while in Tuscany a regional law it inflicts most damage upon riparian vegetation, in which it forbids its use for reforesting, green area maintenance and tends to become dominant, altering ecosystem properties, consolidation purposes. Removal actions have been promoted displacing other species and, consequently, reducing local in retrodunal systems in this region.

23 CARPOBROTUS SP.PL.

HOTTENTOT FIG

Growth form: shrub Family: Aizoaceae Native range: South Africa (Cape Province) Introduction: ornamental

The importance of the species belonging to this genus consists Photo E. Carli in the fact that they tend to spread in one of the most vulnerable systems, i.e. on small islands, and in one of the few habitats that are still relatively untouched by man, i.e. steep sea cliffs, both of which still contain important endemisms. Although they are Photo E. Carli highly ornamental and have very striking flowers, the expansion of these succulent, crawling species probably poses one of the most serious threats to biodiversity in Italy, and certainly the worst posed by a plant. Indeed, it threatens not only diversity on a local scale, but the survival itself of rare and endemic taxa, such as Centaurea horrida in Sardinia and some endemic Limonium species in the Tuscan Archipelago (in Elba, Giglio and Capraia, B.Foggi, (pers. comm.) and the Pontine Islands (in Ventotene). Carpobrotus species form large, dense mats that outcompete the pre-existing vegetation. They can modify soil properties such as nutrient contents and pH. Their presence all along the coastline is due both to interventions aimed at stabilising the dunes and to its widespread cultivation by the management Photo F. Pretto of seaside facilities and private owners on account of their attractive flowers and easy propagation. The invasion of these species continues to this day, because they are widely available commercially and because they may be spread by means of even very small fragments that root at nodes. Several entities belonging to the Carpobrotus genus, including hybrids, probably exist in Italy. In local botanical studies, however, two main entities have been treated distinctly, C. edulis and C. acinaciformis, with Photo J. Grapow information on their distribution and history of introduction being collected separately. It was agreed that this distinction be maintained in the present work until the taxonomy of this group of plants is revised. C. edulis (bottom photo and The establishment of C. acinaciformis (top photo and map) was map) reproduces mainly by first recorded in 1856 on the island of Ischia, off the coast of means of seeds, dispersed above Naples. It is currently invasive in many areas in central and all by small mammals. In contrast southern Italy; it spreads mainly by vegetative means, to what has been observed in the competing with the native species, even at the root level, for rest of the Mediterranean, in Italy water and nutrients. Strategies aimed at containing its spread C. edulis is less widespread than and removal actions have been implemented in Sardinia, while C. acinaciformis, even though in Tuscany a regional law forbids its use for green area they are used equally frequently maintenance and consolidation purposes. in gardens and beach facilities.

24 HERACLEUM MANTEGAZZIANUM SOMMIER & LEVIER

GIANT HOGWEED Photo J. Grapow

Growth form: perennial herb Family: Apiaceae Native range: Caucasus Introduction: ornamental

Following the observation of some spontaneous, flowering samples at 2,173m on the slopes of the Mont Blanc (see photo), giant hogweed is reported to be the non-native species found at highest altitude in Italy. The first record of this plant in the country, though cultivated, is provided by the photo taken in 1899 by Emil Levier, who had Italy. Moreover, if we consider that it is one of the most significant introduced it in Europe, via Florence, in 1890, on his return from a invasive species in Europe, and that its water-dispersed seeds may botanical trip to the Caucasus mountains. It has since been spread downstream along the entire course of the Po, the longest cultivated as a botanical curiosity, on account of its height (despite river in Italy, which flows eastwards for more than 600 kilometres, being a grass species, it can grow to a height of 5 metres) and the it becomes clear that the management of these populations, which size of its inflorescences (umbels), which may exceed 50 cm in have resisted numerous attempts over the years to control them, is diameter. This species has escaped from cultivation and established of utmost importance. The threat posed by this species is related in Alpine valleys in several areas, though in only one region is it above all to health issues, insofar as it causes serious skin burns, in considered to be invasive. It has rapidly expanding populations, the presence of UV radiation, when human skin come into contact which first developed in a wasteland and then spread along the with the phytotoxic sap contained inside the plant, which may seep banks of the Dora river, an affluent of the Po. The origin of this plant out of broken or damaged leaves and branches. Besides, this species in the Caucasus mountains renders it particularly resistant to the is highly competitive and forms dense stands, and its large leaves environmental conditions in the Alps and it has considerable shade the surrounding area and inhibit the growth of other species, potential to spread and establish in extensive areas in northern thereby reducing species diversity (Pyšek et al. 2007).

IMPATIENS GLANDULIFERA ROYLE

HIMALAYAN BALSAM

Growth form: annual herb Family: Balsaminaceae Native range: Indian Subcontinent Introduction: ornamental

Widely, but still rather patchily distributed throughout northern Italy, this species, whose flowers are very striking, is becoming one Photo P. Ferrari of the main invaders of freshwater wetlands, and is widely reported to dispersal of seeds, which are ejected from the fruits at considerable be spreading rapidly. Imported as an ornamental from the distances, have a highly negative impact on biodiversity. In the Alps Himalayan region, it was recorded in Italy for the first time in the it is one of the few species that spread at high elevations, adapting early 20th century. It establishes in natural riparian habitats, along to the extreme conditions in the mountains, which probably stream and river banks, the shores of lakes and edges of ponds, resemble those found in the area it comes from in the Himalayas. where it progressively displaces other vegetation, creating dense Other species of the same genus have been reported in Italy; these populations over extensive areas. The speed at which it spreads and include I. balfourii and I. parviflora, which are also invasive, but are the ease with which it colonises new sites, thanks to its efficient less widespread in riparian habitats.

25 LUDWIGIA PEPLOIDES (KUNTH) P.H.RAVEN SUBSP. MONTEVIDENSIS (SPRENG.) P.H. RAVEN

WATER PRIMROSE

Growth form: perennial herb Family: Onagraceae Native range: N, C & S America Introduction: ornamental

Reports of the spontaneous occurrence of this species in Italy are very recent, it having been observed for the first time in Lombardy in 1998. It has, since then, spread rapidly to other provinces within the same region, and to the neighbouring Emilia-Romagna. It is an aquatic plant that develops dense populations and consequently displaces the pre-existing vegetation. In other countries, the considerable amount of plant biomass produced by this species has been shown to Photo M. Adorni result in less oxygen being dissolved in water, increased water acidity, eutrophication and increased sedimentation, all of which alter the overall function of the ecosystem environments it could invade and its marked invasiveness, (see e.g. http://www.eppo.org/QUARANTINE/quarantine.htm). which has rendered this species one of the most harmful to the Besides its ecological impact, the rapid spread of this plant conservation of biodiversity in natural freshwater habitats hampers some human activities, such as those related to elsewhere, it may constitute a very serious threat in the future. navigation and irrigation. It invades canals, where it flourishes in This species, and other even more localised species, should the summer and autumn. In Italy, it is thus still relatively rare, thus be monitored closely, since prevention and early response but given the rate at which it spreads, the high number of are, to date, still the most effective control strategies.

Photo M. Adorni

26 PRUNUS SEROTINA EHRH.

BLACK CHERRY

Growth form: tree Family: Rosaceae Native range: N & C America Introduction: ornamental

Originally introduced as an ornamental, the use of this species for plantation forestry and reforestation has favoured its spread in natural areas in northern Photo G. Ceffali Italy, turning it into one of the most invasive plant species in the Po Plain in recent decades. It invades forest understorey, wood clearings, coppices and invasion of this species is accompanied by an overall change in the wetlands. It reproduces rapidly both by means of bird-dispersed ecosystem and a marked impoverishment in the quality of the seeds and root sprouts. It can survive for long periods of time in woods (see e.g. Starfinger et al. 2003). Several initiatives aimed at the lower layers of woods, enduring both the shade and eradicating this species have been promoted in Italy within the competition. As soon as there is a break in the canopy, due to context of the various LIFE Natura projects felling or fallen trees, it rapidly prevails over all other species. The (http://ec.europa.eu/environment/life/index.htm).

REYNOUTRIA JAPONICA HOUTT.

JAPANESE KNOTWEED

Growth form: perennial herb Family: Polygonaceae Native range: China & E Asia Introduction: ornamental

Listed among the worst 100 invasive species in the world (www.issg.org) and in Europe (www.daisie.eu), Reynoutria Photo L. Ghillani japonica is, along with other species and hybrids of the same are deprived of vegetation and are consequently easily eroded. genus (such as R. ×bohemica), currently one of the most invasive The seeds are dispersed by the wind, though male flowers appear species in the non-native flora even in Italy. It was introduced in to be rare in invasive populations, most of the seeds being the Padua Botanical Garden in the mid 19th century as an generated by the pollen of other, related species such as R. ornamental, and was subsequently cultivated, even outside parks sachalinensis. and gardens, to consolidate soil. Reports of its spontaneous The invasiveness of this species is due above all to its vigorous occurrence date back to at least 1875, following which it has vegetative growth, starting from even very small fragments of spread at an alarming rate. It is now found throughout northern rhizome. Its spread is thus fostered by various forms of both Italy, even at high elevations in the Alps. Its favourite natural and anthropic disturbance, such as erosion of river banks, environments are the sides of roads and railways, waste areas and extraction of materials from rivers and soil movements. The river banks; it spreads along the banks of rivers thanks to the persistence and regenerative capacity of the abundant root water, which carries fragments of its rhizomes downstream. sprouts from the rhizomes explains why keeping this species under Although it prevails in disturbed environments, it also tends to control is a particularly challenging task (see e.g. Child, Wade invade natural areas, where it forms dense clonal stands that 2000). Nevertheless, an effort must be made to prevent it from oppress and outcompete other species, thereby preventing their spreading in natural areas, at least in isolated populations, such as survival. Thus, when the epigeal parts fall in autumn, large areas those at high elevations in the Alpine valleys.

27 ROBINIA PSEUDOACACIA L.

BLACK LOCUST

Growth form: tree Family: Fabaceae Native range: USA Introduction: ornamental

The black locust, which is the consolidation of banks, erosion control and reforestation most common invasive tree in purposes. It is a fast growing, extremely prolific, deciduous tree Italy, abounds throughout the that reproduces very efficiently, mainly by producing shoots country. It was introduced as a from its root system. It spreads spontaneously in a wide range garden ornamental and was of habitats, owing to its tolerance to a variety of environmental already present in 1662 in the conditions. It is an early successional species that colonises Padua Botanical Garden. It was wasteland, rapidly growing into large, dense thickets that immediately appreciated for the displace other vegetation, change the structure and beauty of its flowers and foliage, composition of the invaded habitat, and modify the chemical as well as for its rapid growth composition of the understorey by nitrogen fixation. Although and vigorous root system, composed of strong, resistant, it spreads in riparian habitats and open woods, particularly in underground rhizomes. It was thus cultivated in urban parks central and northern Italy, its favourite environments are and as a street tree, and was subsequently spread extensively disturbed habitats, where, once established, it is difficult to by farmers and foresters to produce firewood and for the control, owing above all to its extensive rhizome system.

Photo L. Ghillani

28 References

CELESTI-GRAPOW L., ALESSANDRINI A., ARRIGONI P.V., ASSINI S., BANFI E., BARNI E., BOVIO M., BRUNDU G., CAGIOTTI M.R., CAMARDA I., CARLI E., CONTI F., DEL GUACCHIO E., DOMINA G., FA- SCETTI S., GALASSO G., GUBELLINI L., LUCCHESE F., MEDAGLI P., PASSALACQUA N.G., PECCENINI S., POLDINI L., PRETTO F., PROSSER F., VIDALI M., VILLANI M.C., VIEGI L., WILHALM T. & BLASI C. 2009a. Non-native flora of Italy: species distribution and threats. Plant Biosystems. In press. CELESTI-GRAPOW L., ALESSANDRINI A., ARRIGONI P.V., BANFI E., BERNARDO L., BOVIO M., BRUNDU G., CAGIOTTI M., CAMARDA I., CARLI E., CONTI F., FASCETTI S., GALASSO G., GUBELLINI L., LA VALVA V., LUCCHESE F., MARCHIORI S., MAZZOLA P., PECCENINI S., POLDINI L., PRETTO F., PROSSER F., SI- NISCALCO C., VILLANI M.C., VIEGI L., WILHALM T. & BLASI C. 2009b. The inventory of the non- native flora of Italy. Plant Biosystems 143. In press. CELESTI-GRAPOW L., PRETTO F., BLASI C. (Eds). 2009c. Flora alloctona d’Italia. Palombi Edi- tori, Roma. In press. CHILD L., WADE M. (Eds). 2000. The Japanese knotweed manual: the management and control of an invasive alien weed. Packard Publishing Ltd. 152 pp. CONTI F., ABBATE G., ALESSANDRINI A., BLASI C. (Eds). 2005. An annotated Checklist of the Ital- ian Vascular Flora. Palombi Editori, Roma. 420 pp. DAISIE 2009. Handbook of Alien Species in Europe. Springer. 400 pp. ELTON C.S. 1958. The ecology of invasions by animals and plants. Methuen, London. 181 pp. GALASSO G., CHIOZZI G., AZUMA M., BANFI E. (Eds.). 2008. Le specie alloctone in Italia: cen- simenti, invasività e piani di azione. Memorie Soc. It. Sc. Nat. Mus. Civ. St. Nat. Milano, 36(1): 1-96. KOWARIK I., SÄUMEL I. 2007. Biological Flora of Central Europe: Ailanthus altissima (Mill.) Swingle. Perspectives in Plant Ecology, Evolution and Systematics 8 (4): 207-237. PIGNATTI S. 1982. Flora d’Italia. Edagricole, Bologna. 3 vols. PYŠEK P., COCK M.J.W., NENTWIG W., RAVEN H.P. (Eds.) 2007. Ecology and management of Giant Hogweed (Heracleum mantegazzianum). CAB International. 324 pp. PYŠEK P, RICHARDSON DM, REJMÁNEK M, WEBSTER GL, WILLIAMSON M, KIRSCHNER J. 2004. Alien plants in checklist and floras: towards better communication between taxonomists and ecologists. Taxon 53(1):131-143. REJMÁNEK M, RICHARDSON DM, PYŠEK P. 2004. Plant invasion and invasibility of plant communities. in: Van Der Maarel, Eds. Vegetation Ecology. Blackwell Publishing, Malden. pp. 332-355. RICHARDSON D.M., PYŠEK P., REJMÁNEK M., BARBOUR M.G., PANETTA F.D., WEST C.J. 2000. Nat- uralization and invasion of alien plants: concepts and definitions. Diversity & Distribution 6:93-107. RIVAS-MARTÍNEZ S., PENAS A., DÍAZ T.E. 2001. Biogeographic Map of Europe 1:16.000.000. University of León, Spain. STARFINGER U., KOWARIK I., RODE M., SCHEPKER H. 2003. From desirable ornamental plant to pest to accepted addition to the flora? The perception of an alien plant species, Prunus serotina, through the centuries. Biological Invasions 5 (4): 323-335. WEBER E. 2003. Invasive plant species of the world. A reference guide to environmental weeds. CAB International. 548 pp.

29 CONTENTS OF THE CD-ROM

Non-native flora of Italy

Celesti-Grapow L., Pretto F., Carli E. & Blasi C. (Eds.) 2009

5 6 7 8

database E. Dominici

Supports Windows 98SE/Me/2000/Xp only

30 Non-native flora of Italy regions that runs down the Peninsula, we adapted the map so For each of the 1,023 species of the non-native vascular flora of as to provide greater detail on a national scale by following Italy, the attached CD-ROM contains the following information: the boundary of the Mediterranean region proposed in the “Biogeographic Map of Europe” of Rivas-Martinez et al. (2001); nd or empty=no data available. 1 Search – to search for a species, click on the button and type the name. If the name has changed, the current name will 9 Land use – the distribution of each species in land use types appear. was recorded using the CORINE Land Cover classification system, a standard land cover classification of the data for 2 Name – each species or subspecies is identified by its scien- Europe (http://www.apat.gov.it/site/it-IT/) structured hier- tific name, according to the botanical nomenclature archically in five levels. The occurrence of the species in Land adopted by Celesti-Grapow et al. 2009b. Cover types was assessed, at the most detailed level possible, by experts in each regional group; when the informa- 3 Name in previous floras – the name as it is found in the tion was transferred from the regional level onto a national most recent Italian Flora (Pignatti 1982) and in the most re- scale, the data were often simplified to level 1 or to level 2. cent checklist of the Italian flora (Conti et al. 2005) is listed under the current one. 10 Threat – the information available on the threats that the species pose was integrated into a simple unified system 4 Family – the attribution of each species to a family follows comprising two broad categories, i.e. socio-economic and Celesti-Grapow et al. 2009b. environmental, each of which was subdivided into several classes to obtain the following preliminary scheme: 5 Status in Italy – it refers to the invasion status of the species Socio-economic threat – including: agricultural weeds, e.g. in Italy, i.e. whether the species is casual, naturalized, local that cause losses in production or additional, control-related invasive, invasive, or has not been recorded since 1950. costs in arable land (crops), pastures, nurseries, greenhouses, plantations and water management; species that damage 6 Residence time – whether the species is an archaeophyte or man-made constructions (e.g. buildings, infrastructures, neophyte. monuments and archaeological remains); species that threaten livestock (e.g. toxic to farm animals); species that 7 Native range – identifies the geographical provenance of threaten human health – e.g. allergenic, toxic or poisonous each species. Besides the main categories, e.g. Europe, North species; species that cause dermatitis (e.g. urticants). America, South America (including Central America) and Environmental threat – including: species that target other Australasia, we used intercontinental groups, such as biota (e.g. competition for space, nutrients, water and light); Mediterranean (i.e. the Mediterranean Basin), Eurasia and hybridization with a related native species or variety Tropics, and “wide distribution” to refer to those species with generally inducing a loss of genetic diversity in native plants; extensive native distribution ranges across different conti- abiotic changes (e.g. modification of soil chemical-physical nents, or whose provenance cannot be determined more ac- properties, nutrient availability, water regime/balance). We curately. Moreover, we referred to as “uncertain” those assigned each species to one, or several, of the afore- species whose geographical origin is unknown or uncertain, mentioned classes as long as they were included in and as “hybrid” species resulting from hybridization. specialised studies conducted on Italy. (Medit.=Mediterranean; Temp.=Temperate; Trop.=Tropical). 11 Map of the distribution in Italy – The occurrence and sta- 8 Biogeographical Region – we adopted the classification of tus of each species in the 21 regions was compiled by each the “Map of the Biogeographical Regions of Europe” (Euro- regional group using data published in the literature, inte- pean Environmental Agency, http:/www.eea.europa.eu), ac- grated with herbaria records and some unpublished data; an cording to which Italy comprises three regions: Alpine, exhaustive field survey aimed at updating the distribution Continental and Mediterranean. However, as regards the of the species throughout the country was not possible boundary between the Continental and the Mediterranean within the framework of this project.

31 Buddleja davidii. Photo D. Bouvet Acknowledgements This study is part of

“A survey of the non-native flora of Italy”,

a research project funded by the Italian Ministry for the Environment, Nature Protection Directorate. This publication would not have been possible without the contribution of many experts involved in the project national

Ministry of Environment, Land and Sea Protection Via Cristoforo Colombo, 44 I - 00147 Rome Telephone: +39 06 57 221 www.minambiente.it

Nature Protection Directorate Via Capitan Bavastro, 174 I - 00154 Rome Telephone: +39 06 57 22 87 22 – 06 57 22 87 05 Fax: +39 06 57 22 87 07 www.minambiente.it [email protected]; [email protected]

Italian Society of Botany Via G. La Pira, 4 I - 50121 Firenze Telephone: +39 055 27 57 379 fax: +39 055 27 57 467 www.societabotanicaitaliana.it [email protected]

Interuniversity Research Center “Biodiversity, Plant Sociology and Landscape Ecology” Sapienza University of Rome – Department of Plant Biology P.le Aldo Moro, 5 I - 00185 Roma Tel. +39 06 49 91 25 61 Fax +39 06 49 91 24 37 www.uniroma1.it/cirbfep [email protected]